1. Field of the Invention
The present invention relates to an apparatus for feeding a high consistency fluid onto a rotating face, more specifically an ink feeder and an ink scraper most suitable for use in an offset rotary press.
2. Description of the Prior Art
An apparatus for feeding a high consistency fluid onto a rotating face comprises an ink feeder for feeding ink onto a printing plate.
FIG. 24 is a partial side view showing structure of one color part of an offset rotary press in the prior art which prints using a so-called keyless ink feeder. As shown in FIG. 24, there is provided an ink fountain roller 1 which is driven by a motor which is able to conduct speed control independent of a main body of the printing machine so as to rotate the roller 1 at a speed which is lower than that of the main body of the printing machine so that ink can be transferred. Ink of a constant film thickness is fed onto an outer circumferential surface of the ink fountain roller 1 from a portion of an ink feed blade 12 which is disposed along the axial direction (widthwise direction) of the ink fountain roller 1, or the cross machine direction. Also, there is maintained a gap of a predetermined distance between the ink feed blade 12 and the surface of the ink fountain roller 1 during printing.
In the prior art ink feed blade 12, as used in the keyless ink feeder for a high consistency fluid, there is no ink feed blade sectioned in the widthwise direction of the ink fountain roller 1. Color change in the widthwise direction of the ink fountain roller 1 thus cannot be effected.
So, an ink feed blade 12 in which a plurality of ink tanks 2 are provided in the widthwise direction of the ink fountain roller 1 so as to be sectioned to each feed ink uniformly in the widthwise direction onto the ink fountain roller 1 has been provided.
In FIG. 24, there is provided an ink transfer roller 3 which is driven to rotate at the same speed as that of the main body of the printing machine. The ink transfer roller 3 and the ink fountain roller 1 which is fed with ink are urged toward each other so that, while slippage between both rollers is being effected at a nip portion thereof, slip metering is taking place and the ink is transferred onto the ink transfer roller 3. Then, the ink is fed from the ink transfer roller 3 to a roller group 4 comprising a plurality of rollers and is further fed onto a printing plate 6 which is attached to an outer circumferential surface of a plate cylinder 45 via a form roller 5 in the roller group 4.
In the case of an offset printing, the printing plate 6 is also fed with damping water from a damping device 29 in addition to the ink fed as mentioned above.
The ink as fed onto the printing plate 6 via the ink fountain roller 1, the ink transfer roller 3 and the roller group 4 is fed with a constant film thickness in the cross machine direction. The ink is further transferred from the printing plate 6 to a blanket cylinder 46 so that printing is made on a paper running between the blanket cylinder 46 and another blanket cylinder 46 disposed opposingly thereto.
There is a portion where no printing is made, that is, a portion where no ink is fed onto the printing plate 6 from the form roller 5. Therefore, although the ink of a constant film thickness is fed, that ink is not consumed and the ink film thickness corresponding to that portion on the outer circumferential surfaces of the roller group 4, etc. becomes thicker.
So, a scraping doctor 8 is caused to abut on a doctor roller 7 disposed in the roller group 4. By use of this scraping doctor 8, the ink at the portion of the roller group 4 where the film thickness becomes thicker is scraped so that the ink is consumed uniformly in the entire widthwise direction of the roller group 4. Thus even if ink is fed constantly in the widthwise direction of the roller group 4, it is consumed with a good balance, and even though there occurs a differential ink consumption locally during the printing, a uniform ink film thickness is maintained in the cross machine direction.
In such keyless inking in which ink is fed without use of an ink quantity regulating mechanism divided into small sections in the cross machine direction, it has been a large problem as to how high consistency ink can be used to obtain high quality printed matter.
In order to solve this problem, an apparatus for realizing a high quality printing is disclosed by Japanese utility model application No. Hei 2(1990)-8147 titled "Ink receiving tank for keyless inking apparatus".
In the apparatus, as illustrated in FIG. 24, a shaft 9 fitted with a spirally formed plate (hereinafter referred to as "vane wheel 9") is disposed at a bottom portion of the ink tank 2, and by use of this vane wheel 9, ink is fed to an opening portion of an ink suction pipe 44 of an ink pump 10 disposed at the bottom portion of the ink tank 2.
It is to be noted that the ink received in the ink tank 2 contains water, which has been fed from the damping device 29 onto the printing plate 6, either transmitted on the surfaces of the roller group 4 etc. or scraped in the form of a mixture in the ink. The vane wheel 9 has at the same time a function of agitating the water mixed in the ink in the ink tank 2 for the purpose of homogenization.
As for the vane wheel 9 driven in the ink tank 2, as shown in FIG. 25 an independent drive motor 50 is provided, and this drive motor 50 is arranged in parallel with the ink tank 2.
In FIG. 24, the ink pump 10 is driven by an independent motor 49 and is separately disposed in parallel with the ink tank 2. Thus ink is sucked into the ink suction pipe 44 from the bottom portion of the ink tank 2 to be discharged through an ink feed pipe 11 and to be fed to the ink feed blade 12.
The ink suction pipe 44 and ink feed pipe 11 for transferring the ink are both long pipes.
In the case where a color printing is made by the offset rotary press having an ink feeder as so constructed, a different color of ink is sometimes applied to each sheet (page) of paper that is to be printed and disposed in the widthwise direction of the blanket cylinder 46. For this purpose, attempts are being made to have the ink feeder sectioned in the cross machine direction so that a different color of ink can be fed to each section in the widthwise direction of the blanket cylinder 46 for printing each sheet of paper.
Furthermore, with respect to such an ink pump system of an ink feeder as used in a relief printing, there is disclosed an ink feeder driven for each sheet of paper by way of mechanical drive or motor drive, as seen in the U.S. Pat. No. 2,731,914 "Inking mechanism for printing machines" or the U.S. Pat. No. 3,366,051 "Inking mechanism for printing machines".
FIG. 26 is a detailed cross sectional view of one example of a prior art ink feeder used in an offset rotary press having a keyless ink feeding system of which the entire structure is shown in FIG. 24.
As shown in FIGS. 24 and 26, ink 2a is fed onto the ink fountain roller 1 which is driven by a speed control motor (not shown) to rotate at a slightly lower speed than that of the main body of the printing machine. The ink fountain roller 1 is adjusted to a predetermined film thickness via a gap at a tip end of the ink feed blade 12 portion. The ink 2a is fed through a nip portion formed between the ink fountain roller 1 and the ink transfer roller 3, which is driven to rotate at a speed of the main body of the printing machine. The ink 2a is fed downstream to the ink transfer roller 3, the ink roller group 4, and further to the printing plate 6 via the form roller 5.
In case of an offset printing generally, the printing plate 6 is also fed with damping water from the damping device 29.
The ink 2a, transferred in a constant quantity in the cross machine direction, is further fed from the printing plate 6, attached around the plate cylinder 45, onto the blanket cylinder 46 so that a printing is made on a paper which is running in contact with the blanket cylinder 46. Thus, at a portion where no printing is made, the ink 2a is not consumed and the ink film thickness does not become thinner.
In the middle of the ink roller group is a doctor roller 7. The ink 2a is scraped by a scraping doctor 8 which abuts the doctor roller 7. Therefore, the ink 2a is consumed throughout in the cross machine direction so that the ink 2a, fed uniformly in the cross machine direction, is consumed in a good balance.
In keyless inking systems in which ink is fed without using an ink quantity regulating mechanism divided into small sections in the cross machine direction, it is necessary to use ink 2a of as high a consistency as possible to obtain high quality printed matter.
In the prior art ink feeder 100, a vane wheel 9, fitted with a spiral plate around an outer circumference of a shaft 31, is provided at a bottom portion of an ink tank 2. The vane wheel 9 is for agitating the ink 2a and for assisting movement of the ink 2a toward a suction port of the ink pump 10. The vane wheel 9, positioned within the ink tank 10, is rotated by a drive motor (not shown).
The ink 2a is fed from the ink pump 10 to an ink feed nozzle 511 via an ink feed pipe 11 and then is transferred to an ink feed blade 12 portion following the rotation of an ink fountain roller 1.
For a color printing, etc., it is necessary to change the color of the ink 2a for each sheet of paper in the cross machine direction. To accomplish this, the ink feeder 100 is sectioned into plural sets (2 to 4 sets, for example) in the cross machine direction so that the ink 2a of a different color is fed for each sheet of paper.
It is to be noted that while a printing is being done, a gap between the ink feed blade 12 and a surface of the ink fountain roller 1 is kept at a constant, predetermined distance. However, the ink feed blade 12 of a keyless ink feeder for a high consistency fluid has not been sectioned for each sheet of paper. It has been formed in one integral unit in the axial direction of the ink fountain roller 1.
In FIG. 26, ink 2a is fed from an ink tank 2 into an ink feed pipe 11 by an ink pump 10 via a pipe coupling 333 and then is injected onto the surface of the ink fountain roller 1 from an ink feed nozzle 511. The ink 2a is then transferred rotationally on the ink fountain roller 1 in the direction of the arrow in FIG. 26. The ink 2a is regulated to a constant film thickness by an ink feed blade 12 so that the ink 2a can be further transmitted onto an ink transfer roller 3 through a nip portion.
Residual ink on the surface of the ink fountain roller 1 after the ink is so transmitted is transferred rotationally to be scraped by a scraper 334 fitted right below the ink feed nozzle 511. The surplus ink, scraped by the scraper 334 and the ink feed blade 12, falls down to be recovered in the ink tank 2.
In the ink feeder 100, the ink feed nozzle 511 and the ink feed blade 12, fitted to a support member 151, are both fixed to a frame. As shown in FIG. 26, the support member 151 and the ink feed blade 12 can be moved rotationally around a fulcrum shaft 329 to a state of chain line when a color change of ink 2a or cleaning of the ink feed blade 12 is to be done for maintenance services, etc.
When a color change of ink 2a is to be done, the pipe coupling 333, positioned midway through the ink feed pipe 11, is first uncoupled so that an ink tank 2 of a next order is replaced. The pipe coupling 333 is then coupled, and a drive source coupling 13, mounted to the printing machine side, and a driven coupling 14 of the ink pump 10 side are coupled. The ink pump 10 is driven to feed new ink, which pushes out old ink so that the ink 2a is replaced. Contaminated mixture of ink and wash liquid is recovered in a separate recovery tank (not shown), and after replacement of the ink is completed, the next printing is started.
FIGS. 27 and 28 show a schematic structure of an ink scraping doctor portion in an offset rotary press. In the figures, numeral 3 designates an ink transfer roller, numeral 7 designates a doctor roller, numeral 8 designates a scraping doctor abutting an outer circumference of the doctor roller 7 and numeral 218 designates a scraping doctor support device for supporting the scraping doctor 8.
In the offset rotary press shown in FIGS. 24 to 28, ink 2a, injected onto an ink fountain roller 1 which is driven by a speed control motor (not shown) to rotate at a slightly lower speed than that of the main body of the printing machine, is regulated to a predetermined film thickness via a gap at a tip of an ink feed blade 12 portion. Then, the ink 2a is fed through a nip portion formed between the ink feed blade 12 and an ink transfer roller 3 which is driven to rotate at a same speed as that of the main body of the printing machine. The ink 2a is fed downstream to the ink transfer roller 3 and to an inking roller group 4 for receiving the ink 2a. The ink 2a is further fed to a printing plate 6 via a form roller 5.
It is to be noted that a residual ink on a surface of the ink fountain roller 1 is transferred rotationally to be scraped by a scraper 334 fitted right below an ink feed nozzle 511. The residual ink scraped by the scraper 334 and the ink feed blade 12 falls down to be recovered in an ink tank 2.
In the offset press generally, damping water is fed onto the printing plate 6 from a damping device. The ink 2a, transferred in a uniform quantity in the cross machine direction, is further fed from the printing plate 6, attached around the plate cylinder 45, onto a blanket cylinder 46 so that a printing is made on a paper which is running in contact with the blanket cylinder 46. Thus, at a portion where no printing is made, the ink 2a is not consumed and the ink film thickness does not become thinner.
As a method for stabilizing such an irregular film thickness of ink 2a, a method is provided wherein the ink 2a is scraped by a scraping doctor 8 abutting a doctor roller 7 positioned in the middle of an inking roller group so that the ink 2a is recovered throughout in the cross machine direction. Even if the ink is fed uniformly in the cross machine direction, the ink is consumed in a good balance.
While a color printing is made, in which different colors are arranged in the cross machine direction, the ink feeder 100 is constructed so that the roller is sectioned in a plural number (2 to 4, for example) of widthwise sections, and ink 2a of a different color is fed for each sheet of paper. It is to be noted that the gap between the ink feed blade 12 and the surface of the ink fountain roller 1 is set to a predetermined distance while the printing is being done.
On the other hand, as shown in FIGS. 27 and 28, since the scraping doctor 8 is formed as one unit extending throughout in the axial direction of the doctor roller 7, it functions well when the ink for each sheet of paper is the same in the widthwise direction. However, if the ink 2a is different for each sheet in the widthwise direction of the roller, adjacent ink of different colors is mixed and collected in a contaminated state.
So, in the ink feeder shown in FIGS. 24-26, and in the ink scraping device shown in FIGS. 27 and 28, there are problems to be solved as follows:
(1) In the prior art ink feeder shown in FIGS. 24 and 25:
In this kind of ink feeder, the vane wheel 9 disposed in the ink tank 2 and the motor shaft of the ink pump 10 are positioned separately from and parallel with each other, and the ink tank 2 and the ink pump 10 are apart from each other. Therefore, the ink suction pipe 44 for sucking ink from the ink tank 2 to the ink pump 10, and the ink feed pipe 11 for feeding ink from the ink pump 10 to the ink feed blade 12 become long and their structures also become complicated due to the arrangement.
Accordingly, the piping flow resistance becomes larger. Especially in the elongated ink suction pipe 44, which must take in the ink of a high-consistency fluid, a problem of insufficient suction flow is easily caused.
Also, a drive mechanism for the vane wheel 9 for moving the ink to the opening portion of the ink suction pipe 44 in the ink tank 2 is needed. In addition, a drive motor 49, 50 (see FIG. 25) for driving the vane wheel 9 and the ink pump 10, respectively, becomes necessary.
Further, when a color printing is to be made in type of printing machine, there is sometimes a necessity for changing colors of ink for each sheet of paper to be printed in the widthwise direction of the blanket cylinder 46, as mentioned above. But because the ink feed blade 12 is not sectioned in the cross machine direction, a problem is that this color printing cannot be produced.
Also, even in the ink feeder, including the prior art ink feed blade 12, which is sectioned in the cross machine direction so that a color of ink can be changed for each sheet of paper in the cross machine direction, it is necessary to change the ink feeder, including the ink tank 2.
As mentioned above, however, the ink suction pipe 44 and the ink feed pipe 11 are elongated, and the two drive motors 49 and 50 are provided. Thus the weight of the ink feeder when it is removed from the main body of the printing machine becomes heavier and treatment of electric wires becomes necessary. So, a problem is that attachment and detachment of the ink feeder to and from the main body of the printing machine becomes difficult and work time therefor also becomes longer.
(2) In the prior art ink feeder shown in FIG. 26:
Color change of ink is done by work procedures as mentioned above. Thus, for change of ink to a new ink which is neither contaminated nor diluted, not only is considerable time needed, but there is also a considerable quantity of contaminated ink to be abandoned at the initial stage of the ink change. Also, in this kind of ink feeder, the drive source coupling 13 and the driven coupling 14 must be connected only after they are set to a predetermined engagement position. Thus, if an initial setting for an ink change is neglected, a problem is that connection of the couplings becomes impossible.
Further, since an ink feed blade 12 formed in one unit throughout in the widthwise direction of the ink fountain roller 1, is provided, the inks of adjacent positions in the cross machine direction may mix with each other. This may cause the printing quality to be greatly damaged. In addition, the gap control of the ink feed blade 12 in its longitudinal direction is difficult to maintain, and the gap at the tip of the ink feed blade 12 varies in the widthwise direction of the roller due to variation in the fluid pressure for ink feed and the pressure (reaction force) of the ink scraping. Consequently, it becomes difficult to maintain ink feed in a uniform film thickness throughout in the axial direction of the ink fountain roller 1, and a thick and thin irregularity of color of the printed surface occurs.
Also, at the time of attachment and detachment of the ink feeder 100, a problem is that ink 2a falls and scatters from the ink feed nozzle 5, the ink feed blade 12 portion, the pipe coupling 333, etc. and contaminates the surroundings of the printing machine. Also, problems are that it takes a considerable time to attach and detach the pipe coupling 333, and that it is less workable and takes time to remove the residual ink on the ink feed nozzle 511, the ink feed blade 12, etc.
(3) In the prior art ink scraper shown in FIGS. 27 and 28:
In the offset press, printing of plural sheets (4 sheets for example) is sometimes done at one time by use of one set of blanket cylinders which each have different colors of ink. In the prior art, as shown in FIGS. 27 and 28, a means to scrape the ink 2a, remaining on the surfaces of the inking roller group after printing includes the use of a single scraping doctor 8. This scraping doctor 8 extends the length of the inking rollers in the axial direction so as to abut the doctor roller 7. For this reason, a problem is that an adjacent color of ink may mix with other colors on the printing plate side so as to cause a dull color, and the aesthetic quality of the printing is greatly damaged.
Although a means for storing the scraped ink in order not to cause such a dull color has been provided, because all of the scraped ink is stored in such a way, there is a need to either enlarge the ink tank, replace the ink frequently, or to abandon it.